Dental drill and method for producing same

ABSTRACT

The invention relates to a method for producing a dental drill that has a shank ( 1 ) and a work section. The shank contains a centrally arranged, continuous first channel ( 3 ). The work section contains one or more continuous, spiral-shaped further channels ( 4   a,    4   b ). The first channel and the further channels open into a common chamber ( 5 ) connecting the shank and the work section. The shank is sintered with the work section in order to form a one-piece, sintered component that encloses the chamber connecting the shank and the work section.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of PCT/EP2012/050852 filed onJan. 20, 2012, which claims priority under 35 U.S.C. §119 of GermanApplication No. 10 2011 000 352.5 filed on Jan. 27, 2011, thedisclosures of which are incorporated by reference. The internationalapplication under PCT article 21(2) was not published in English.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a dental drill and a method for productionthereof.

2. The Prior Art

Dental drills of one-piece construction are already known, which includea shank and an adjoining work section having one or more cutting edges,the drill being furnished in the interior of the shank with a centralcoolant channel. This coolant channel serves, in working operation ofthe dental drill, for the purpose of transporting a coolant,particularly a cooling liquid, into the region of the work section whereit is used for cooling the work section and the currently treated toothof a patient.

In known dental drills of that kind the said coolant channel opens intothe transition region between the shank and the work section so thatcoolant already issues in the region of the rear end of the work sectionand thus directly cools merely the rear part of the work section. Adisadvantage of drills of that kind is that only inadequate cooling ofthe cutting region of the dental drill and also inadequate cooling ofthe currently treated tooth of the patient take place.

A dental drill having a shank and a work section connected with theshank is described in DE 10 2009 043 875.0. The shank includes acentrally arranged, continuous first channel. The work section has oneor more continuous, helically extending further channels. Providedbetween the shank and the work section is a gap into which the firstchannel and the further channels open. The shank and the work sectionare connected together by means of clamping sleeve, a solderedconnection or an adhesive connection.

SUMMARY OF THE INVENTION

The object of the invention consists in indicating a method of producinga dental drill and a dental drill with improved cooling of the cuttingregion, which drill does not require any additional connecting materialin the transition region between the shank and the work section,particularly any clamping sleeve, solder material or also adhesivematerial.

This object is fulfilled by a method with the features according to oneaspect of the invention or by a dental drill with the features accordingto another aspect of the invention. Advantageous embodiments anddevelopments of the invention are discussed below.

The advantages of the invention consist particularly in that a dentaldrill is provided which in the transition region between the shank andwork section has no visible seam location or joint location. Moreover,no connecting materials are provided in this transition region, such as,for example, solder material, adhesive material or a clamping sleeve.This has the advantage that the bio-compatibility of the dental drill isimproved. In this connection it is of significance that a dental drillduring tooth treatment has contact with the lips, tongue and teeth of apatient. Due to the non-presence of connecting materials such as aclamping sleeve, solder material or adhesive material it is ensured thatno materials harmful to the human organism can be absorbed by way of themucous membrane of the patient and thereby place the health of thepatient at risk. Moreover, in advantageous manner patients who haveallergies to the material of the clamping sleeve, solder connection oradhesive connection can be prevented from coming into contact with thesematerials.

A further advantage of the invention is that creation of sealingproblems in the transition region between the shank and the work sectionis excluded. This is attributable to the fact that through the sinteringof the shank with the work section the particles present in the surfaceregion of the shank mix with the particles present in the surface regionof the work of the work section in such a manner that a joint-freeconnection of the shank with the work section arises. Consequently,there are no visible seam locations or joint locations through whichcooling liquid could undesirably escape during operation of the dentaldrill.

Moreover, in the case of a dental drill according to the invention it isensured that the cooling liquid is guided without pressure loss up tothe end region, which is remote from the shank, of the helicallyextending further channels and issues at that point so that the cuttingregion of the dental drill and also the treated tooth of the patient arecooled in desired manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantageous characteristics of the invention are evident fromthe exemplifying explanation thereof by way of the figures, in which:

FIG. 1 shows a longitudinal sectional illustration of a dental drillaccording to a first embodiment of the invention,

FIG. 2 shows a longitudinal sectional illustration of a dental drillaccording to a second embodiment of the invention,

FIGS. 3A, 3B, 3C, and 3D show diagrams for explanation of a method ofproducing a dental drill according to the invention and

FIGS. 4A and 4B show a longitudinal sectional illustration of a dentaldrill according to a third embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Dental drills according to the invention have a shank and a worksection, wherein the shank has a centrally arranged, continuous firstchannel, the work section has one or more continuous, helicallyextending further channels, the first channel and the further channelsopen into a common chamber connecting the shank and the work section andthe shank and the work section are sintered together. A design of thatkind of a dental drill creates the possibility of transporting, duringworking operation of the dental drill, a sufficient quantity of coolant,particularly cooling liquid, directly to the cutting region of the worksection of the dental drill so that cooling, which is improved bycomparison with known dental drills, of the cutting region and thecurrently treated tooth of the patient is achieved.

FIG. 1 shows a diagram of a longitudinal sectional illustration of adental drill according to a first embodiment of the invention. Thisdental drill has a cylindrically formed shank 1 and a similarlycylindrically formed work section 2. A continuous first channel 3extending in axial direction is centrally provided in the shank 1. Thediameter of the shank 1 is denoted by d1.

Provided in the work section 2 of the dental drill are two continuous,helically extending further channels 4 a and 4 b which communicate withthe cutting region 2 b of the work section 2. The diameter of the worksection 2 is denoted by d2 and corresponds with the diameter d1 of theshank 1.

A chamber 5 is provided in the interior of the dental drill in thetransition region from shank 1 to work section 2. In the case of theembodiment shown in FIG. 1 this chamber 5 is of disc-shapedconstruction. Not only the first channel 3, but also the two helicalfurther channels 4 a and 4 b open into the chamber 5, which canalternatively also be constructed to be slot-shaped, cylindrical,polygonal or conical.

In working operation of the dental drill, for example for thepreparation of a jawbone for later reception of an implant or forremoval of caries from a tooth of a patient a coolant, particularly acooling liquid, is delivered under low pressure into the first channel 3from the bottom in FIG. 1. The coolant runs through the rectilinearlyformed first channel 3, fills the chamber 5 provided in the transitionregion from the shank 1 to the work section 2, penetrates from thechamber 5 into the helically extending further channels 4 a and 4 b,runs through these and is then delivered in the cutting region 2 b ofthe work section 2. Consequently, not only the cutting region formingthe work region of the dental drill, but also the currently treatedtooth of the patient are directly cooled by the coolant issuing from thechannels 4 a and 4 b.

The shank 1 and the work section 2 of the dental drill can consist ofthe same material or of different materials. The shank 1 preferablyconsists of steel, ceramic, hard metal or plastic and the work section 2of steel, ceramic or hard metal. The cutting region 2 b of the worksection 2 can consist of the same material as the remaining part of thework section 2 or also of another material.

FIG. 2 shows a diagram of a longitudinal sectional illustration of adental drill according to a second embodiment of the invention. Thisdental drill has a cylindrically formed shank 1 and a similarlycylindrically formed work section 2. A continuous first channel 3extending in axial direction is centrally provided in the shank 1. Thediameter of the shank 1 is denoted by d1.

Provided in the work section 2 of the dental drill are two continuous,helically extending further channels 4 a and 4 b communicating with thecutting region 2 b of the work section 2. The diameter of the workregion 2 is denoted by 2 and corresponds with the diameter d1 of theshank 1.

A chamber 5 is provided in the interior of the dental drill in thetransition region from the shank 1 to the work section 2. In the case ofthe embodiment shown in FIG. 2 this chamber 5 is constructed to beconical, but can also have a different shape. Not only the first channel3, but also the two helical further channels 4 a and 4 b open into thechamber 5. In the illustrated embodiment the chamber 5 is provided inthe shank 1. Alternatively thereto it can also be provided in the worksection 2. A further alternative consists in providing a part of thechamber in the shank 1 and the other part of the chamber in the worksection 2.

In working operation of the dental drill, for example for removal ofcaries from a tooth of a patient, a coolant, particularly a coolingliquid, is introduced under pressure into the first channel 3 from thebottom in FIG. 2. The coolant runs through the rectilinearly formedfirst channel 3, fills the chamber 5 provided between the shank 1 andthe work section 2, penetrates from the chamber 5 into the helicallyextending further channels 4 a and 4 b, runs through these and is thenissued in the cutting region 2 b of the work section 2. Consequently,not only the cutting region, which forms the work region of the dentaldrill, but also the currently treated tooth of the patient are directlycooled by the coolant issuing from the channels 4 a and 4 b.

The shank 1 and the work section 2 of the dental drill can consist ofthe same material or of different materials. Preferably, the shank 1consists of steel, ceramic, hard metal or plastic and the work section 2of steel, ceramic or hard metal. The cutting region 2 b of the worksection 2 can consist of the same material as the remaining part of thework section 2 or also of a different material.

FIGS. 3A to 3D shows diagrams for explanation of a method of producing adental drill according to the invention. In that case, production of thedental drill shown in FIG. 1 is explained on the basis of FIGS. 3A and3B and production of the dental drill shown in FIG. 2 is explained onthe basis of FIGS. 3C and 3D.

For production of the dental drill shown in FIG. 1 initially a shank 1and a work section 2 are produced independently of one another. Theshank 1 is shown in FIG. 3B. The work section 2 is illustrated in FIG.3A.

For production of the shank 1, plastic material is extruded by a firstextrusion tool in such a manner that a first body, which consists ofplastic material, with a centrally arranged, continuous first channelissues from the first extrusion tool. The first body issued from thefirst extrusion tool is of cylindrical construction and has a diameterd1. The body issued from the first extrusion tool is cut to apredetermined length l1 and then dried so that its consistencysolidifies.

For production of the work section 2, plastic material is extruded by asecond extrusion tool in such a manner that a second body, whichconsists of plastic material, with rectilinearly extending furtherchannels issues from the second extrusion tool. The body issued from thesecond extrusion tool is similarly of cylindrical construction. It has adiameter d2 which corresponds with the diameter d1 of the shank. Thesecond body issued from the second extrusion tool is cut to apredetermined second length l2. The cut-to-length second body issubjected to a uniform twisting of a rolling motion, the speed of whichconstantly changes over the entire length l2, by means of a frictionsurface arrangement while being supported over its entire length.Helically extending further channels 4 a and 4 b, as illustrated in FIG.3A, are thereby formed from the initially rectilinearly extendingfurther channels. The body produced in this manner is dried so that itsconsistency solidifies. The chamber 5, which in the illustratedembodiment is of rectangular form, is ground into the rear region of thedried body. The cutting region 2 b is similarly formed in the frontregion of the dried body by means of a grinding process.

Thereafter—as is illustrated between FIGS. 3A and 3B by the arrows x—thebodies solidified by drying are placed against one another in axialdirection and heated. This heating is carried out in such a manner thatthe mutually adjoining surfaces of the heated bodies melt and that themutually adjoining surfaces are sintered together in such a manner thatafter connection thereof no seam locations or joint locations arevisible. The sintered-together bodies are subsequently dried again sothat the consistency thereof further solidifies.

A one-piece sintered component, which completely encloses the chamber 5connecting the shank 1 and the work section 2, is formed by theafore-described sintering of the shank to the work section.Consequently, the transition region between the shank and the worksection is free of additional connecting materials of any kind.

For producing the dental drill shown in FIG. 2 initially a shank 1 and awork section 2 are produced independently of one another. The shank 1 isshown in FIG. 3D. The work section 2 is illustrated in FIG. 3C.

For production of the shank 1, plastic material is extruded by a firstextrusion tool in such a manner that a first body, which consists ofplastic material, with a centrally arranged, continuous first channel 3issues from the first extrusion tool. The first body issued from thefirst extrusion tool is of cylindrical construction and has a diameterd1. The body issued from the first extrusion tool is cut to apredetermined length l3 and then dried so that the consistency thereofsolidifies. The chamber 5, which in the illustrated embodiment is ofconical construction, is ground into the front region of the dried body.

For production of the work section 2, plastic material is extruded by asecond extrusion tool in such a manner that a second body, whichconsists of plastic material, with rectilinearly extending furtherchannels issues from the second extrusion tool. The body issued from thesecond extrusion tool is similarly of cylindrical construction. It has adiameter d2, which corresponds with the diameter d1 of the shank. Thesecond body issued from the second extrusion tool is cut to apredetermined second length l4. The cut-to-length second body issubjected to a uniform twisting of a rolling motion, the speed of whichconstantly changes over the entire length l4, by means of a frictionsurface arrangement while being supported over its entire length.Helically extending further channels 4 a and 4 b, as illustrated in FIG.3C, are thereby formed from the initially rectilinearly extendingfurther channels. The body produced in this manner is dried so that theconsistency thereof solidifies. The cutting region 2 b is formed in thefront region of the dried body by means of a grinding process.

Thereafter—as illustrated between the FIGS. 3D and 3C by the arrowsx—the bodies solidified by drying are placed against one another inaxial direction and heated. This heating is carried out in such a mannerthat the mutually adjoining surfaces of the heated bodies melt and thatthe mutually adjoining surfaces are sintered together in such a mannerthat after connection thereof no seam locations or joint locations arevisible. The bodies sintered together are subsequently dried again sothat the consistency thereof further solidifies.

A one-piece sintered component, which completely encloses the chamber 5connecting the shank 1 and the work section 2, is formed by theafore-described sintering of the shank to the work section.Consequently, the transition region between the shank and the worksection is free of additional connecting materials of any kind.

FIG. 4A shows a longitudinal sectional illustration of a dental drillaccording to a third embodiment of the invention. In this thirdembodiment the chamber 5 provided in the transition region from theshank 1 to the work section 2 is of slot-shaped construction. The widthof the chamber 5 in the radial direction of the dental drill is matchedto the radial external dimensions of the helically extending channels 4a and 4 b so that the chamber 5 does not protrude in radial directionoutwardly beyond the helically extending channels. This is also apparentfrom the illustration on the righthand side of FIG. 4B, wherein thisillustration shows a cross-sectional illustration of the dental drillalong the section line S shown by a dot-dashed line on the lefthand sideof FIG. 4A.

In the case of the afore-described embodiments the shank in eachinstance has a centrally arranged central channel. According to amodified form of embodiment a dental drill can also be constructed insuch a manner that the helically extending channels provided in the workregion extend as far as the shank and also run completely through theshank. In this case the feed of coolant is provided into the gripmember, which is not illustrated in the figures, of the dental drill.

A chamber can, by way of example, similarly be provided there, throughwhich chamber the cooling liquid supplied from a cooling liquid sourceis conducted onward in the helically extending channels of the dentaldrill.

The chamber 5 is in radial direction of the drill broader than the firstcontinuous channel 3 in shank 1. Also end regions of the furtherchannels 4 a, 4 b opening into chamber 5 are still helically twisted.

REFERENCE NUMERAL LIST

-   1 shank-   2 work section-   2 b cutting region of the work section-   3 first channel-   4 a, 4 b further channels-   5 chamber-   d1 diameter of the shank-   d2 diameter of the work section-   l1, l3 length of the shank-   l2, l4 length of the work section

The invention claimed is:
 1. Dental drill with a shank (1) and a worksection (2), wherein the shank has a centrally arranged, continuousfirst channel (3), the work section has more than one internalcontinuous, helically extending further channels (4 a, 4 b), a chamber(5) is provided between the shank and work section, the first channeland the further channels open into the chamber and the shank and thework section form a one-piece component which is connected by sinteringand which completely encloses the chamber (5) connecting the shank (1)and the work section (2), wherein the transition region between theshank and the work section is free of additional connection materials,wherein the transition region between the shank and the work section hasno visible seam locations or joint locations and wherein the chamber isdisc-shaped; and the chamber (5) is in radial direction of the drillbroader than the first continuous channel (3) in shank (1); and endregions of the further channels (4 a, 4 b) opening into chamber (5) arestill helically twisted.
 2. Dental drill with a shank (1) and a worksection (2), wherein the shank has a centrally arranged, continuousfirst channel (3), the work section has more than one internalcontinuous, helically extending further channels (4 a, 4 b), a chamber(5) is provided between the shank and work section, the first channeland the further channels open into the chamber and the shank and thework section form a one-piece component which is connected by sinteringand which completely encloses the chamber (5) connecting the shank (1)and the work section (2), wherein the transition region between theshank and the work section is free of additional connection materials,wherein the transition region between the shank and the work section hasno visible seam locations or joint locations and wherein the chamber (5)is slot-shaped; and the chamber (5) is in radial direction of the drillbroader than the first continuous channel (3) in shank (1); and endregions of the further channels (4 a, 4 b) opening into chamber (5) arestill helically twisted.
 3. Dental drill with a shank (1) and a worksection (2), wherein the shank has a centrally arranged, continuousfirst channel (3), the work section has more than one internalcontinuous, helically extending further channels (4 a, 4 b), a chamber(5) is provided between the shank and work section, the first channeland the further channels open into the chamber and the shank and thework section form a one-piece component which is connected by sinteringand which completely encloses the chamber (5) connecting the shank (1)and the work section (2), wherein the transition region between theshank and the work section is free of additional connection materials,wherein the transition region between the shank and the work section hasno visible seam locations or joint locations and wherein the chamber (5)is polygonal; and the chamber (5) is in radial direction of the drillbroader than the first continuous channel (3) in shank (1); and endregions of the further channels (4 a, 4 b) opening into chamber (5) arestill helically twisted.
 4. Dental drill with a shank (1) and a worksection (2), wherein the shank has a centrally arranged, continuousfirst channel (3), the work section has more than one internalcontinuous, helically extending further channels (4 a, 4 b), a chamber(5) is provided between the shank and work section, the first channeland the further channels open into the chamber and the shank and thework section form a one-piece component which is connected by sinteringand which completely encloses the chamber (5) connecting the shank (1)and the work section (2), wherein the transition region between theshank and the work section is free of additional connection materials,wherein the transition region between the shank and the work section hasno visible seam locations or joint locations and wherein the chamber (5)is conical; and the chamber (5) is in radial direction of the drillbroader than the first continuous channel (3) in shank (1); and endregions of the further channels (4 a, 4 b) opening into chamber (5) arestill helically twisted.
 5. Dental drill with a shank (1) and a worksection (2), wherein the shank has a centrally arranged, continuousfirst channel (3), the work section has more than one internalcontinuous, helically extending further channels (4 a, 4 b), a chamber(5) is provided between the shank and work section, the first channeland the further channels open into the chamber and the shank and thework section form a one-piece component which is connected by sinteringand which completely encloses the chamber (5) connecting the shank (1)and the work section (2), wherein the transition region between theshank and the work section is free of additional connection materials,wherein the transition region between the shank and the work section hasno visible seam locations or joint locations and wherein the chamber (5)is cylindrical; and the chamber (5) is in radial direction of the drillbroader than the first continuous channel (3) in shank (1); and endregions of the further channels (4 a, 4 b) opening into chamber (5) arestill helically twisted.